There is a requirement for Internet Banking and Financial Services Applications, to keep information (such as account details, PIN numbers etc.) available and secure when a user swaps between web pages. The user may swap pages within a site, for example, when conducting on-line banking and swapping from one account transaction to another; or when a user swaps between pages on different sites such as from their bank's web site to a utility, supermarket or airline web site. It is important, if such inter- or intra-site commerce is to be conducted, for data relating to the user to be persistent between web pages, because requesting the user to enter a card number or PIN multiple times is not viable from a usability viewpoint.
A `cookie` mechanism, described at "http://home.netscape.com/newsref/std/cookie_spec.html", attempts to overcome this problem. This mechanism, however, is both unwieldy and not guaranteed to be successful as the acceptance of cookies is a browser determined function.